The present invention relates generally to a coupling for connecting corrugated tubing with a fitting, and more particularly to a coupling which includes an internally-received, split ring member which facilitates the assembly of the coupling.
Corrugated tubing, often fabricated of stainless steel, copper, or the like and jacketed with a plastic material, is commonly employed in residential or commercial building constructions as a transitional fluid conduit extending between an appliance or other machine and a rigid auxiliary line, pipe, or other connection of a fuel source which typically is natural gas, propane, or the like. The flexibility of such tubing facilitates the alignment of couplings and other connections, and also accommodates limited movement of the appliance or machine with respect to the rigid connection of the fuel source.
More recently, tubing of such type has been proposed as a substitute for traditional hard, i.e., inflexible, steel or iron "black" pipe in gas line applications residential and commercial construction. Again, the flexibility of the tubing facilitates its installation through walls, ceilings, and floors and, especially, the alignment of the tubing connections. Such tubing, moreover, is lightweight, easy to carry, requires no threading or heavy equipment therefor, allows the use of fewer fitting connections, and exhibits less leak potential than conventional, hard piping. Corrugated tubing of the type herein involved additionally is used in other fluid transport applications such as in air conditioning, hydraulics, and general plumbing, and also as conduit for electrical applications.
It is common practice to terminate either or both of the distal ends of a length of corrugated tubing with a coupling for providing a leak-free connection or other transition, and/or for effecting a mechanical locking of the tubing ends limiting their movement under pressure or force. For example, U.S. Pat. Nos. 5,441,312; 4,630,850; 4,674,775; and 2,323,912 disclose couplings of such type which generally comprise a sleeve and a cap nut. The sleeve and nut are coaxially received over a distal end of the tube for connection to a fitting associated with the auxiliary line or the appliance.
Commonly-assigned, co-pending provisional application U.S. Ser. No. 60/017,227, filed May 9, 1996, discloses a coupling for connecting a distal end of a corrugated tube with a fitting having a forward coupling end with a tapered surface. The coupling includes a collet having a circumferential wall portion which extends axially from a forward first end to a rearward second end. The second end is configured as having an outer portion and an inner portion of a second diameter smaller than the outer periphery of the tube. The inner portion is configured to be receivable within the root portions of the tube for retaining the collet thereon, and presents a generally rearwardly-facing compression surface. The wall portion is longitudinally dissected through the second end thereof into at least a pair of arcuate, cantilevered segments. Each segment is resiliently yieldable for radial outward movement allowing the tube crest portions to be received through the second end of the wall portion as the collet is advanced forwardly over the distal end of the tube into retention within one of the root portions. A fastening member is journalled over the collet second end and is engagable with the coupling end of the fitting to draw the collet and the distal end of the tube toward the fitting. The fastening member has an inner radial surface extending to a rearwardly-facing shoulder portion configured to abuttingly engage the outer portion of the collet second end for urging the collet rearwardly toward the fitting compressing at least the first crest portion of the fitting distal end between the tapered surface of the fitting and the compression surface of the collet.
Young, U.S. Pat. No. 2,549,741, discloses a pipe joint which includes a coupling nut adapted for a threaded connection with a spigot member. The coupling nut has an internal groove for receiving a split ring, and the spigot member has a conical surface for receiving the flared surface of a pipe. Upon the tightening of the nut on the spigot member, the split ring is made to compresses the flared pipe surface against the spigot.
Sasa et al., U.S. Pat. No. 4,904,002, discloses a fluid coupling for a corrugated pipe which includes a body having a fluid passage, and an outer sleeve having a collar which retains a pair of C-rings. The outer sleeve is adapted to reduce the diameter of the C-rings such that the rings are forced into the root portions of the corrugated pipe wherein the rings are held axially in position.
Sasa et al., U.S. Pat. No. 5,080,405, discloses another coupling for corrugated pipe which includes an inner cylindrical section having an annular groove for receiving a split ring. The groove extends from a forward flange portion to a rearward tapered surface which is formed on the groove. Upon the insertion of an end of the pipe into the cylindrical section, the ring is urged into a corrugation of the corrugated pipe by the tapered surface of the groove.
Sasa et al., U.S. Pat. No. 5,292,156, discloses another fluid coupling for a corrugated pipe. The coupling includes a locking cylinder having a groove which accommodates the radial expansion of a ring received therein when the end of a corrugated pipe is inserted into the cylinder.
Hughes, U.K. Patent No. 1,371,609, discloses another joint for a corrugated pipe which includes a fitting to which a nut is threadably connected. The nut is formed as having a groove portion for retaining a split compression ring. Upon the insertion of an end of the pipe into the nut, the split ring is urged into a into a corrugation of the pipe. The nut then may be tightened on the fitting for drawing the pipe inward into a fluid-tight connection.
Marrison et al., U.S. Pat. No. 5,226,682 discloses a coupling including a first and second member and an annular locking ring interposable therebetween. For receiving the locking ring, the first member is provided as having an exterior surface with a groove, and the second member is provided as having an inner surface with a cavity. The first and second members are secured together when the locking ring is engaged in the groove ands the cavity.
Another coupling for corrugated tubing is marketed commercially by Titeflex Corp., Springfield, Mass. As is described in the Titeflex publication "Gastite.TM. Design and Installation Guide," April 1996, such coupling employs a two-piece metal split ring for positioning a swivel nut. The nut is slidably mounted over the end of the tubing, and the split rings are positioned in the valley, i.e., root or trough, of the first convolution of the corrugations. The nut then is advanced toward the end of the tubing to capture the split rings. A socket flaring tool next is threaded into the nut and tightened. The tightening of the flaring tool compresses the first convolution of the tubing to form a flared seat. The nut lastly is threadably engaged with a corresponding end of the fitting.
However, the provision of two-piece split rings has been observed to complicate the assembly of the coupling. For example, as being of a relatively small size and separate from the nut, there is the potential for the rings to be lost or simply forgotten during installation. One or both of the rings might also fall out of the tubing prior to the connection of the nut to the fitting. If either of the rings is accidentally omitted, the tubing cannot be sealed to the fitting and a hazardous leak may result.
As the use of corrugated tubing in gas line and other fluid transfer applications continues to increase, it will be appreciated that further improvements in the design of couplings therefor would be well-received by both industry and consumers alike. A preferred design would be economical to manufacture, but would also simplify the assembly of the coupling while providing a connection which minimizes the potential for leaks and the like.